I've quickly scoured the forums and haven't seen this mentioned or discussed anywhere, so I decided to go ahead.

Today I have finally completed my 10th artifact research on the huntress in beta and received the chapter 5 lore bit for artifacts. While Thas'dorah's was pretty generic, a bit about Titanstrike seems pretty interesting, especially in the light of the recent interview with Crafticus and Muffinus and "secrets in Legion". You can see the screenshot of the chapter attached to the message. I've started the research for the next Knowledge level, but it will take quite a long time to complete.

Now, I will easily admit that I might be digging too deep as I've been very persistent about there just having to be something about Skoll and Hati, considering everything - mentions of both worgs together (the whole mythology bit, by Thorim during acquiring artifact, even if it is not implemented fully), Hati only interacting with Skoll (smacking him with lightning), Thorim's Peak in Stormheim, etc.

The bit about devilsars made me look through the list of all available models for them, just in case, and some of them can be tracked down to Isle of Giants and Isle of Thunder. While Isle of Giants sure has a lot of "scaly things", Isle of Thunder seems like a better fit to the "Island far to the south", given its name, the whole island revolving around thunder and lightning (Throne of Thunder, The Thunder King, previously being a residence of Ra-den, known as The Storm, etc.) and the skies, which also seem to match the description. I've ran a bit around the Isle, killing lightning-charged mobs, interacting with anything interactable (and trying to with un-interactable), and wondering how to unlock Nalak <The Storm Lord>, who apparently is not present on the beta servers.

My guess is that it's Isle of Giants, since the thunder and lightning in that story aren't from the Thunder King. And he would have gotten his storm powers before that story happened, since he was emperor pre-sundering, and that story presumably takes place post-sundering (if it's isle of giants or isle of thunder).

Titanstrike and Isle of Thunder interaction sounds promising. I found and killed Nalak on the PvP beta server (premade 100 with a fully unlocked artifact). Nothing happened. I even used the ability from the weapon. Isn't the Serpent Bite skin the hidden appearance with Titanstrike? I don't think we have a source yet for it, do we?

That all being said, I think "hunting ground" fits Isle of Giants more. I went to both on Beta and dinked around, nothing stuck out to me. Interesting find though!

Yep, seems like Isle of Thunder is a no, considering pre-Sundering it wasn't even an island, but a mountain. Following is from wowpedia:

Thousands of years ago, the Isle of Thunder was known as the Thundering Mountain, home to the mogu's master, Storm Keeper Ra. During the Great Sundering the mountain sank down beneath the waves, with only the peak staying above the sea as an island.

Just in case ran a bit around Isle of Giants, killed Oondasta (whom I still dearly wish was tameable), ran to the Historian Evelyna, who is a daily quest giver on the Timeless Isle. Nada. It's quite possible that even if something related to "isle far to the south" is actually a thing, it isn't implemented in the beta since that seems to be the only way to keep things a secret before Legion actually goes live. I wish Thorim would recognize Skoll during the artifact scenario, though... But then again, it's Thorim. *cough* You... I remember you... In the mountains! *cough*